Wireless communications between remotely located communicating devices may be implemented using radio frequency (RF) technology. Radio frequency communications have continued to improve through recent decades. Relatively sophisticated components are commonplace enabling radio frequency communications at microwave frequencies in compact components and at reasonable cost.
Some exemplary applications utilizing radio frequency technology include identification applications including, for example, locating, identifying, and tracking of objects. Radio frequency identification device (RFID) systems have been developed to facilitate identification operations. For example, one device may be arranged to output and receive radio frequency communications and one or more remotely located device may be configured to communicate with the one device using the radio frequency communications. The remotely located device may be referred to as a tag, while the other device may be referred to as a reader. Some advantages of radio frequency communications including exemplary radio frequency identification device communications include abilities to communicate without contact or line-of-sight, at relatively fast speeds, and with robust communication channels.
Radio frequency systems typically enable communications between devices located at increased distances compared with inductively coupled identification device systems. Even with radio frequency systems, it may be desired in some communication system applications to increase or maximize a communications range between the remotely located devices. Alternatively or additionally, it may be desired to reduce the transmitting power of the reader device in a particular application. Accordingly, it may be preferred to increase the sensitivity of a tag of the system to provide improved wireless communications between the remotely located devices.
Some aspects of the present invention described below provide wireless communication devices having increased sensitivity.